An adhesive tape attaching jig (50) that allows adhesive tape, which widens along its length, to be continuously attached to an adherend in a stable and reliable manner. The attaching jig (50) has a construction comprising the combination of a tape holder (11, 12) which receives and holds adhesive tape in the attaching jig, a tape attacher (9) which contact bonds the adhesive tape that has been guided from the tape holder (11, 12) onto the tape attachment surface of an adherend, and a jig guide member (6, 7) which continuously guides the attaching jig (50) along the adherend, wherein the tape holder (11, 12), the tape attacher (9) and the jig guide member (6, 7) each also comprise movable mechanisms (26, 31, 32).